A Green Project

What Ron and Juanita started in 1982 as a roadside flower stand has grown into Marlin's Plant Kingdom, a greenhouse with 21,000 square feet enclosed and an additional 40,000 square feet of outside bedding plots.  As the cost of propane for heating their greenhouses soared, Ron began to consider installing a solar heating system in an effort to cut his $35,000 heating bill.  Area experts advised him that the only reasonable approach was to install a geothermal system at a cost of $350,000 (out of the question for a small business owner-operator like Marlin).  Undeterred, Ron designed a solar hot water system that he calculated would save him 10% on his heating costs with an initial investment of $39,000.

The system consists of two 2300 gallon tanks filled with water that is circulated through solar panels during the day, heating it to around 110 degrees.  At night, the flow to the solar panels is turned off and the water is circulated through three hot water heat exchangers in the greenhouse.  The tanks are concrete, specially cast and installed by an area manufacturer of septic tanks.  The tanks are set with their tops about 24 inches below the bottom of the solar panels and a vacuum valve drains the panels at night when the flow is stopped, preventing freezing in the panels at night.  Each tank rests on 6x6 treated wood timbers with blue board insulation between the timbers to insulate them from the ground underneath.  A four inch layer of spray foam insulation applied to the sides and top of each tank completes the shell of heat preservation within the tanks.  The eight solar panels , 4 feet by 10 feet each were purchased from Heliodyne and were installed by ECI Wind and Solar of Matthews, Indiana.  A small electric pump runs the whole system from inside one of the greenhouses.

So, what's been learned?  So far, over a 3 month period from September to December, Ron's heating bill was reduced by a little over 10% compared to the previous year with the same number of heating degree days.  That qualifies as a success in his view.  Based on his experience so far, he plans to add solar panels, perhaps twice the number he has now, and at least one more tank.

Installation of solar panel

The Storage Tanks

The Piping System

The Trenching

The Plumbing System Inside the Greenhouse

Insulating the holding tanks

In the summer of 2011, Ron's inventive mind spurred another innovation.  This time he designed a waste oil recovery burner to heat the water within his auxiliary heating system.

As the crisp fall air cools the evenings, Ron's new system begins its startup.  Consuming just a bit over one gallon per hour, the boiler maintains a constant 123.5 degree heat to the water reserve supply.  This, in turn, supplies the heating needs for nearly 10,000 square feet of his greenhouses.  Modine Fan Coil Units provide the exchange for moving this heat into 3 separate greenhouses.

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